Offshore deepwater mooring systems frequently employ mooring segments that are synthetic. The synthetic mooring segments have length limitations requiring that multiple segments be used in deep locations. Processes of installation, moving, inspection and modifications to the mooring systems require that the segments be lifted onto an offshore work vessel and be restrained to perform the required operations.
The lifting of mooring segments along with supporting anchors and seabed chain lengths above the seabed, develop significant tension due to the gravity loads. These tension levels can exceed 20 tons.
Mooring segments must be separated when a winch drum or storage reel is full or when it is necessary to change or replace a connector in the mooring segment. Prior to separating the mooring segment, it is further necessary to release the tension on the connection to be separated by restraining the subsea side of the mooring segment and transferring the tension from the segment to be separated.
When large diameter synthetic mooring lines are being used, the work vessels may not have sufficiently large deck equipment to restrain the system and allow the connection to be separated. The existing deck mounted restraint equipment is generally not large enough for the larger synthetic ropes proposed for use by the industry.